WATERTOWN, Mass. -- The nation's most wanted man was captured hiding in a backyard boat just a block outside a massive police blockade, bloodied and injured from two gunfights during the manhunt unleashed after he and his brother set off two bombs at Monday's Boston Marathon, authorities said.

Dzhokhar Tsarnaev, 19, was taken by the FBI hostage rescue team just before 8:45 p.m., ending a search that paralyzed the city. He was in serious condition at an area hospital.

The brothers had been on the loose since the marathon but their video images had been a media constant. They surfaced Thursday night, when, police said, they assasinated a campus police officer at the Massachusetts Institute of Technology, and carjacked a Mercedes. After a pursuit and shootout in which they threw explosives at police and injured 15 officers, the older suspect, Tamerlan Tsarnaev, 26, was wounded.

His brother then drove over him, broke through police barricades, then ditched the vehicle and fled on foot into Watertown. The older brother was pronounced dead at 1:30 a.m. Friday.

The younger suspect was discovered just after authorities lifted their lockdown of the city in the early evening.

Over their scanner, Boston police scanner said at 8:42 p.m. that the arrest -- the result of a citizen's tip -- had been made. The news set off a wave of cheers and relief in a city that had been seized by fear of a suspected terrorist on the loose.

"The suspect is in custody," police repeated several times over the airways, quickly followed by a Boston police tweet confirming the news and saying they were sweeping the area for explosives.

The arrest capped a week of high emotions for the nation, from the bombings that killed three people to the fertilizer plant explosion that killed 14 people in West, Texas, and leveled the much of the community.

"All in all, it's been a tough week," President Barack Obama said from the White House shortly after Tsarnaev's capture. "But we've seen the character of our country once more.

"Tonight our nation is in debt to the people of Boston and the people of Massachusetts . . . We have closed an important chapter in this tragedy."

But he said many questions remain: "We will determine what happened and investigate any associations these terrorists may have had."

Obama said he sent his prayers to the family of Sean Collier, the campus police officer who, police said, was executed by the suspects Thursday.

Tamerlan Tsarnaev had an explosive trigger strapped to him when he died, so police were careful in their approach to his brother. They brought in SWAT units, heavy robotic equipment, ambulances and other personnel.

The search ended four days after two pressure cooker bombs went off near the finish line of the Boston Marathon Monday, killing three people and injuring about 180.

The shock and horror of that day gave way to joy and relief Friday night. Residents cheered, chanted "U.S.A." and wildly applauded police vehicles going by.

"We are so happy to be here today," said Col. Timothy Alben, superintendent of the Massachusetts police. "We are eternally grateful for the outcome here tonight. We have a suspect in custody.

"We're exhausted folks but we have a victory tonight. But let's not forget the people along the way," said Alben.

Gov. Deval Patrick said, "There are still questions to be answered," but he thanked the public for tips, saying "this is a night where we're all going to rest easy."

Tom Menino, Boston mayor, thanked authorities. "They worked so hard this week," he said. "I feel so good about this, I tell ya . . . the people of the Boston area can sleep tonight."

Jessica Heath, 30, who lives a few blocks where the suspected bomber was found said, "I am relieved they found him." She said she was glad that he was taken alive, because of all the questions.

"Why," she said. "I think that was the biggest question."

The blasts shook a nation that had not seen such mass violence since Sept. 11, 2001. Police appealed to the public for help in finding the suspects, who were caught on video carrying back packs at the race to zero in on them.

Tweeting under the name @j_tsar, Dzhokhar Tsarnaev, sent a tweet out a few hours after the marathon bombings that said: "Ain't no love in the heart of the city, stay safe people."

And in a photo essay posted on a photoshelter.com website and confirmed by a source as belonging to Tamerlan Tsarnaev, the suspected bomber said in the essay: "I don't have a single American friend. I don't understand them."

Meanwhile, sources have confirmed that federal agents interviewed Tamerlan Tsarnaev in 2011 at the request of a foreign government. They questioned him, and found no links to terror or any threats, the sources said.

The brothers came to the U.S. in 2002 and are of Chechen descent.

Their mother and aunt said they don't believe the brothers were involved and their father said his sons were framed and he described the Dzhokhar as "an angel."

But earlier Friday, Ruslan Tsarni, speaking outside his home in Montgomery Village, Md., told his nephew: "I say, Dzhokhar, if you're alive, turn yourself in and ask for forgiveness!" He added, "He put a shame on this . . . family . . . He put a shame on the entire ethnicity," referring to the fact that the family is of Chechen descent.

Maret Tsarnaeva, a Toronto woman who identified herself as the aunt of the suspects, said at a media briefing that she remained unconvinced that the brothers were responsible for the bombing.

"We're talking about three dead people, 100-something injured, and I do not believe, I just do not believe our boys would do that," she said. "I don't know them in the way that they could be capable of this," Tsarnaeva told reporters in Toronto.

Their mother, Zubeida Tsarnaeva, told CNN that she also thought her sons had been set up by authorities, adding that she was close to her sons and would know if her sons harbored extremist views.

"My oldest son . . . never talked about terrorism," she said. He had become increasingly religious in the recent past, she said, but "He never told me he would be on the side of jihad."

Tsarnaeva said the older brother had not been a devout, practicing Muslim, but about two years ago, that changed. He started praying five times a day, she said: "I don't think anything bad about it. I'd rather him praying than smoking, doing drugs."

She said Tamerlan Tsarnaev was married and had a young daughter. "He was really happy about his daughter," she said.

"They are normal young men," their aunt said. "Tamerlan is almost two meters tall, very athletic, smart boy. Somehow, he did not find himself yet in America because it's not easy."

Tsarnaeva said she filed paperwork for her older brother, the boys' father, to come to the United States.